O`Shaughnessy, John, author
George Allen and Unwin, 1974
Buku Teks
Brech, E.F.L., author
Longmans, Green & Co. , 1957
Buku Teks
Brech, E.F.L., author
Longman , 1970
Buku Teks
Brown, Wilfred
Heinemann, 1971
Buku Teks
Lawrence L. Bethel ... [et al.]
McGraw-Hill, 1945
Buku Teks